Breast drill



Patented Uefa. i6, 1924,

UNITED STATES JESSIE B. BOWMAN, OF MIDDLESBORO, KENTUCKY.

BREAST DRILL.

Application filed March 3, 1924. Serial No. 696,541.

T0 all whom t may concern:

Be it known that l, Jnssrn B. Bowman', a citizen of the United States, residing at Middlesboro, in the county of Bell and State of Kentucky, have invented certain new and useful Improvements in Breast Drills, of which the following is a specification.

rlhis invention relates to a breast drill and has for its obj ect to provide, in a manner as hereinafter set forth, a drill of such class, with a revolvable tool carryingshaft provided at its inner terminus with a reversely bevelled pinion, and said drill further includes a pair of closely arranged manually operated driving elements acting syn-- chronously on said pinion whereby the drill can be operated expeditiously without any inconvenience to the operator, as would not be the case if the driving elements were spaced far apart.

Further objects of the invention are to provide, in a manner as hereinafter setforth, a breast drill which is unusually compact, strong, durable, thoroughly eflicient and convenient in its use, readily assembled, and comparatively inexpensive to manufacture.

With the foregoing and other objects in view, the invention consists of the novel construction7 combination and arrangement of parts, as hereinafter more specificall,v described and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which come within the scope of the claims hereunto appended,

In the drawings wherein like reference characters denote corresponding parts throughout the several views Figure l is a side elevation of a breast drill, in accordance with this invention.

Figure 2 is an elevation taken at right angles to Figure l.

Figure 3 is a fragmentary view, in section, and upon an enlarged scale, of the supporting bar, tool member driving shaft and double bevel pinion carried by the latter.

Figure 4 is a section on line 4 4, Figure 2.

Figure 5 is a section on line 5-5, Figure 2.

Referring to the drawings in detail, 1 denotes a combined positioning and supporting member adapted to extend across the breast and sides of the operator when the device is employed for drilling purposes, and which furthermore enables the device to be forced forwardly when drilling. The member l is of U-shape contour and formed from a strip of metallic material of substantial rigidity and width.

Secured to the forward face of the meniber l, centrally thereof, is a base plate and the hold-fast devices for securing the plate 2 to the member l are indicated at i3y Formed integral with the base plate 2 and projecting forwardly therefrom is a tubular extension l of substantial length and which provides a socket for the reception of the rear end of the supporting bar of the drill.

The supporting bar comprises a rear portion 5 of cylindrical contour which is seated in and secured to the extension 4; in any suitable manner, and said supporting bar further includes a flattened outer portion G.

The iattened outer portion 6 includes a rectangular intermediate part 7, a rear part 8 gradually increasing in width from the portion 5 to the intermediate part 7, and a forward part 9 which gradually decreases in width towards the forward end of the supporting bar. The intermediate part is formed with a rectangular opening l0, and the forward part 9 with a centrally arranged lengthwise extending bore 11, which terminates at one end at the forward end of the supporting bar and at its other end communicates with the opening lO. The part 8, at the forward terminal portion thereof, is formed with a socket l2 extending longitudinally thereof and which coinniunicates with the opening l0 and further is in alignment with respect tothe bore ll, but is of less diameter than the diameter of the bore 1l. The part 8 is furthermore provided intermediate its ends and rearwardly with respect to the socket l2, with a transversely extending socket 13, having a threaded wall. rThe socket 13 intersects the longitudinal center of the part 8 and is arranged rearwardly of the socket l2. The socket 13 opens at one side of the part Fil The part 9 is formed, intermediate its ends and below the bore 11, with a transversely extending socket i4 having its wall threaded and said socket 11i opens at that side of.

the part 9 which is opposite the side of the part 8 through which the socket 12 opens.

The supporting bar preferably is constructed of metallic material somewhat lill light in weight to allow the drill to be easily handled although the supporting bar can be constructed of any suitable material desired.

Secured within the bore 11 is a bearing sleeve 15 of the same length as the length of the bore 11, and extending through said sleeve 11, across the opening 10 and into the socket 6, as well as projecting a substantial distance forwardly from the supporting bar 9, is a revolvable operating shaft 16 for the tool member 17, which is detachably connected to chuck 18, secured on the forward end of the shaftlG.

Arranged within the opening 10 and fixedly secured to the rear terminal portion of the shaft 16, through the medium of a pin 19, is a pinion formed of a pair of cylindrical end portions 20, 21, and an intermediate portion which gradually decreases in diameter from its center towards a cylindrical end portion, as indicated at 22, 23. The intermediate portion of the pinion is so set up that the periphery thereof will be bevelled in opposite directions, and formed integral with the periphery of the intermediate portion of the pinion are two sets of teeth 24, 25, and with the set 24 merging into the set 25, centrally of the pinion and further with the set 24 extending to the cylindrioal portion 20, and the set 25 extending to the cylindrical portion 21. The cylindrical portions 20 and 21 are free of the teeth. The construction set forth provides a double bevel pinion and with each of thev toothed portions of the pinion converging in a direction from the center ofthe pinion towards an end portion thereof.

The end portion 20 is arranged in close proximity to the forward end wall 26 of the opening 10, and the end portion 21 is seated against a plurality of bearing balls 27, which surround the shaft 16 and are seated in a groove 28 formed in the end wall 29 of the opening 10, and also in a groove 30 formed in the end portion 21. The pinion is provided with a medial bore 31 for the passage of the shaft 16, and the groove 30 surrounds the bore 31 and the groove 28 surrounds the socket 12 at the open end thereof. The bearings 27 take up end thrust on the shaft 16 and further facilitate the operation thereof when the teeth 24, 25 are en gaged by a pair of driving elements to be presently referred to.

Projecting laterally from one side of the part 9, is a stub shaft 32 having its inner portion peripherally threaded as at 33 for engagement with the threads of the wall of a socket 14, whereby the shaft 32 is secured to the part 9. Connectedto the part 8 and projecting laterally is a stub shaft 34 having its inner portion peripherally threaded, as at 35', for engagement with the threaded wall of the socket 13, whereby the stub shaft 24 is secured to the part 8. The shafts 32 and 34 are arranged out of alignment, due

to the fact that the socket 14 is offset with respect to the longitudinal center of the supporting bar, and the socket 13 is arranged t the longitudinal center of the supporting Revolvably mounted on the shaft 32 is a driving element in the form of a bevel gear 35, and revolvably mounted on the shaft r34v is a driving element in the form of a bevel gear 36. Each of the gears 35 and 36 is of like construction and each is formed with a hub 37, a solid web 38 and a circular row of bevelled teeth 39 on one side of the web 3S. The hub 37 extends inwardly and outwardly with respect to the web 38 and the inwardly extending portion of the hub of the gear 35 abuts against the part 9 and acts as a spacing medium and the inwardly extending portion of the hub of the gear 36 abuts against the part 8 and constitutes a spacing medium. The teeth 39 of the gear 35 are permanently in mesh with the set of teeth 24, and the teeth 39 of the gear 36 are permanently in mesh with the set of teeth 25.

The shaft 32 projects outwardly from the outwardly extending portion of the hub 37 of the gear 35 and the shaft 34 projects outwardly from the outwardly extending portion of the hub 37 of the gear 36. Mounted on the outer end of the shaft 32, as well as the shaft 34, is a nut 40 and interposed between each nut 40 and the outwardly projecting portion of a huh 37 is a washer 41, and by this arrangement a gear wheel is mounted on a shaft 32 or 34 between a washer and one side of the supporting bar. Fixedly secured to the outer face of each of the gear wheels 35 and 36 is a crank arm 42 provided with a handle 43. The crank arms 42, with their handles, are provided for the purpose of manually revolving the gears 35 and 36 synchronously and on the manual operation of the said gears the teeth 39 there'- of meshing with the sets of teeth 24, 25, will drive the shaft 16, Vcausing thereby the operation of the tool member 17.

The axes of the gears 35, 36 are eccentrically disposed with respect to each other. The axis of the gear 35 is to one side of the longitudinal axis of the pinion provided with the oppositelyextending sets of bevelled teeth 24, 25. The axis of the gear 36 intersects the longitudinal axis of the pinion referred to. The gears 35, 36, or the sets of teeth 24, 25, may be in the form of skew gears, or the teeth of the gears 35, 36 are so arranged whereby they do not engage for vtheir full length and depth the teeth 24, 25, or the sets of teeth 24, 25 so disposed as not to engage for their full length and depth the gears 35, 36. Either of the foregoing arrangements vwill provide for the operation of the tool carrying shaft with the axes of the gears 35, 36 disposed in the manner referred to with respect to the longitudinal axis of the pinion.

Then the drill is to be operated, the member l is positioned against the breast of the operator and the operator then grasps the handles 43 and revolves the gears 35, 36, causing thereby the operation of the tool member 17, and during the operation of the latter, pressure from the operator against the member l will force the tool member into the work during the operation thereof. As the driving elements are arranged in very close relation, such arrangement provides for their convenient operation manually by the operator.

It is thought that the many advantages of a breast drill in accordance with this invention can be readily understood, and although the preferred embodiment of the invention is as illustrated and described, yetit is to be understood that changes in the details of construction can be had which will fall within 'the scope of the invention as claimed.

ll'vhat I claim is l. A. breast drill comprising a supporting bar provided with an opening near its for ward end, a pair of oppositely disposed stub shafts secured to and projecting laterally from said bar, said shafts arranged in proX- imity and one positioned forwardly and the other rearwardly of said opening, a sleeve mounted in said bar forwardly of and communicating with said opening, a revolvable tool member carrying shaft journalled in said sleeve and extending across said opening and into said bar, a one piece double bevel toothed pinion fixed to said revolvable shaft within said opening, and manually operated means mounted on each of said stub shafts and meshing with said pinion for driving it, said rear stub shaft intersecting the longitudinal center of said bar and the other of said stub shafts arranged to one side of the longitudinal center of said bar.

2. A breast drill comprising a supporting bar formed with a iiattened forward terminal portion formed intermediate its ends with an opening, a pair of oppositely disposed stub shafts secured to and projecting outwardly from opposite sides of said flat tened portion and one arranged forwardly and the other rearwardly of said opening, said bar provided with a centrally arranged lengthwise disposed bore centrally thereof, said bore extending from the forward end of said flattened portion and terminating at the forward wall of said opening, a bearing sleeve in said bore, said flattened portion further provided with a socket arranged in alignment with said bore and communicating with said opening through the rear wall thereof, a tool member carrying shaft extending through said sleeve, across said opening and into said socket, a one-piece double bevel pinion fixed to said shaft within said opening, and a manually operated bevel gear wheel mounted on each of said stub shafts and permanently meshing with said pinion for driving the latter.

In testimony whereof, I aflix my signature hereto.

J ESSIE B. BOVMAN. 

